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+* ARM Generic Interrupt Controller
+
+ARM SMP cores are often associated with a GIC, providing per processor
+interrupts (PPI), shared processor interrupts (SPI) and software
+generated interrupts (SGI).
+
+Primary GIC is attached directly to the CPU and typically has PPIs and SGIs.
+Secondary GICs are cascaded into the upward interrupt controller and do not
+have PPIs or SGIs.
+
+Main node required properties:
+
+- compatible : should be one of:
+ "arm,cortex-a15-gic"
+ "arm,cortex-a9-gic"
+ "arm,cortex-a7-gic"
+ "arm,arm11mp-gic"
+- interrupt-controller : Identifies the node as an interrupt controller
+- #interrupt-cells : Specifies the number of cells needed to encode an
+ interrupt source. The type shall be a <u32> and the value shall be 3.
+
+ The 1st cell is the interrupt type; 0 for SPI interrupts, 1 for PPI
+ interrupts.
+
+ The 2nd cell contains the interrupt number for the interrupt type.
+ SPI interrupts are in the range [0-987]. PPI interrupts are in the
+ range [0-15].
+
+ The 3rd cell is the flags, encoded as follows:
+ bits[3:0] trigger type and level flags.
+ 1 = low-to-high edge triggered
+ 2 = high-to-low edge triggered
+ 4 = active high level-sensitive
+ 8 = active low level-sensitive
+ bits[15:8] PPI interrupt cpu mask. Each bit corresponds to each of
+ the 8 possible cpus attached to the GIC. A bit set to '1' indicated
+ the interrupt is wired to that CPU. Only valid for PPI interrupts.
+
+- reg : Specifies base physical address(s) and size of the GIC registers. The
+ first region is the GIC distributor register base and size. The 2nd region is
+ the GIC cpu interface register base and size.
+
+Optional
+- interrupts : Interrupt source of the parent interrupt controller on
+ secondary GICs, or VGIC maintenance interrupt on primary GIC (see
+ below).
+
+- cpu-offset : per-cpu offset within the distributor and cpu interface
+ regions, used when the GIC doesn't have banked registers. The offset is
+ cpu-offset * cpu-nr.
+
+Example:
+
+ intc: interrupt-controller@fff11000 {
+ compatible = "arm,cortex-a9-gic";
+ #interrupt-cells = <3>;
+ #address-cells = <1>;
+ interrupt-controller;
+ reg = <0xfff11000 0x1000>,
+ <0xfff10100 0x100>;
+ };
+
+
+* GIC virtualization extensions (VGIC)
+
+For ARM cores that support the virtualization extensions, additional
+properties must be described (they only exist if the GIC is the
+primary interrupt controller).
+
+Required properties:
+
+- reg : Additional regions specifying the base physical address and
+ size of the VGIC registers. The first additional region is the GIC
+ virtual interface control register base and size. The 2nd additional
+ region is the GIC virtual cpu interface register base and size.
+
+- interrupts : VGIC maintenance interrupt.
+
+Example:
+
+ interrupt-controller@2c001000 {
+ compatible = "arm,cortex-a15-gic";
+ #interrupt-cells = <3>;
+ interrupt-controller;
+ reg = <0x2c001000 0x1000>,
+ <0x2c002000 0x1000>,
+ <0x2c004000 0x2000>,
+ <0x2c006000 0x2000>;
+ interrupts = <1 9 0xf04>;
+ };